1. Field of the Invention
The present invention relates to an ink jet printer and an image recording method.
2. Description of Related Art
An ink jet printer for ejecting ink to a recording medium and recording a desired image on a recording surface of the recording medium has been known well. When so-called cationic polymerization ink, having a cationic polymerization component, is irradiated with UV radiation after it has been ejected by the ink jet printer as a drop on a recording medium at a predetermined position, the ink is cured or polymerized. As a result of polymerization, a dot is formed on the recording medium.
The above-described cationic polymerization ink has humidity dependence. Therefore, the ink may not be cured sufficiently because its sensitivity to UV radiation in a humid environment is lowered. However, when temperature of the ink is raised higher than predetermined temperature (for example, about 40 ° C.), it is possible to prevent the sensitivity of the cationic polymerization ink to UV radiation from being lowered. As a result, to increase the sensitivity of the ink to UV radiation under relatively high humidity, the recording medium is treated at elevated temperatures so as to polymerize ink placed on the recording medium.
When the recording medium is a paper, or the like which is hardly affected by the temperature, elevated temperatures do not cause any significant problems. However, when the recording medium is made of resin or the like, it is affected by the elevated temperatures. Therefore, because the recording medium shrinks or is distorted when heated, heating the recording medium causes image quality to degrade since the recording medium is not precisely conveyed.
Further, it is possible to effectively cure the cationic polymerization ink by irradiating UV radiation of high luminance to the ink. However, because the amount of heat generated from a light source of UV radiation may become large, the temperature of the recording medium is raised. As a result, the same result as the above-described one is caused.